The more awaited revolution

wistfultitleΗλεκτρονική - Συσκευές

24 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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The more awaited revolution



Electronics without silicon is unbelievable, but it
will come true with evolution of diamond or
carbon chip.


Silicon disadvantages:
-



>bulk in size


>slow operating speed


Germanium disadvantages:
-


>large reverse current.


>Less stability towards temperature.


By using carbon as manufacturing material, we
can achieve smaller, faster and stronger chips

2

What is Diamond chip?



Diamond chip is nothing

but carbon chip. Carbon

chip is an electronic chip


manufactured on a

diamond structural carbon

wafer.



The major component

using Carbon is

”CARBON NANOTUBE”





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Carbon
nanotubes

were

discovered in 1991.



It is a
nano

-

size cylinder

of carbon atoms.



They are made of one or several


concentric walls in which carbon atoms

are arranged in hexagonal pattern,


measuring several tens of microns in

length and less than a few nanometers

in diameter.

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1.
Single walled
nanotube
(SWNT)

2.
Multi walled
nanotube
(MWNT)

3.
Torus

4.
Nanobud

5.
Cup stacked carbon
nanotubes
.

5

6


Diameter close to I nm.



Tube length million of times
longer.



Application of SWNT


p
-
FET exposed to oxygen


n
-
FET otherwise.

Hence a NOT logic gate is
created.

7


It has multiple rolled
layers.


Two proposed models:
-


1. Russian model
-



>Concentric.

2. Parchment model
-


>Rolled in around itself

**Special feature
-

Chemical resistance.


8

A nanotorus is a carbon nanotube bent into a
torus i.e.
doughnut shape
.


Nanotori have unique properties:
-



>Magnetic moments 1000 times larger than
previously expected for certain specific radii.

>High thermal stability.

Properties are dependent on radius of the torus

9


Fullerene balls covalently bonded to
underlying
nanotubes
.



PROPERTIES:
-


Good field emitters.


Fullerene molecules act as anchors,
enhancing mechanical properties by
avoiding slipping.



Among the carbon technologies being pursued for
electronics,
graphene

is the most promising for
integration with silicon semiconductor processes.


It is one atom thick planar sheet of sp2 bonded
carbon atoms densely packed in a honeycomb
crystal lattice.


A team has used
graphene

to build a chip known
as a frequency multiplier. Frequency multipliers
take an incoming electrical signal of a certain
frequency and produce an output signal that is a
multiple of that frequency.




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Problems

faced by
graphene
:
-

1.Has a missing band gap thus,

-
acts more like a conductor than a semiconductor.

-
graphene

FETs (field
-
effect transistors) have
terrible on
-
to
-
off current ratios.

2.Heats up considerably when operated at
saturated currents, defeating the purpose of its
usage.

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1.
Strength


.strongest in terms of tensile strength


.stiffest in terms of elastic modulus


.Hollow structure, undergo buckling under


compression.

2.Hardness


Diamond is the hardest material known



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3. Kinetic


In MWNTs inner nanotube core may slide, almost
without friction, within its outer nanotube shell
thus creating an atomically perfect linear or
rotational bearing.

4. Electrical


unique properties dependent on structure


as told by its indices.











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Doping


Very few found. Unlike silicon no


recrystallisation

instead doping after


annealing turns the regions into


graphite amorphous carbon.


Scaling


inability to grow single
-
crystal diamond


across wafers much bigger than an


inch and a half

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SMALLER COMPONENTS ARE POSSIBLE



As the size of the carbon atom is small compared with that of silicon
atom, it is possible to etch very smaller lines through diamond structural
carbon. We can realize a transistor whose size is one in hundredth of
silicon transistor.

IT WORKS AT HIGHER TEMPERATURE


Diamond is very strongly bonded material. It can withstand higher
temperatures compared with that of silicon. At very high temperature,
crystal structure of the silicon will collapse. But diamond chip can
function well in these elevated temperatures.


Diamond is very good conductor of heat
.


So if there is any heat dissipation inside the chip, heat will very quickly


transferred to the heat sink or other cooling mechanics.

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FASTER THAN SILICON CHIP


Carbon chip works faster than silicon chip. Mobility of the
electrons inside the doped diamond structural carbon is higher
than that of in he silicon structure. As the size of the silicon is
higher than that of carbon, the chance of collision of electrons
with larger silicon atoms increases. But the carbon atom size is
small, so the chance of collision decreases.


LARGER POWER HANDLING CAPACITY


For power electronics application silicon is used, but it has
many disadvantages such as bulk in size, slow operating
speed, less efficiency, lower band gap etc at very high voltages
silicon structure will collapse. Diamond has a strongly bonded
crystal structure. So carbon chip can work under high power
environment.. We can connect high power circuit direct to the
diamond chip





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